What is this artifact?

[Larry 1969]

Good day all!
I think my last post on this topic contained too many questions so I've decided to focus on one at a time.
This image is comprised of three consecutive nights of data calibrated with flats, dark flats and bias frames.
There is clearly something wrong. This streak appears in all of my light frames...

I applied flat black paint to everything shiny in my tube (focuser screws and secondary holder attachments). I had a brief clearing so I took advantage.
This image is only 15 minutes of data and it was taken a few weeks later under a full moon. I moved the target center to see what would happen and the smear stayed in the same location as the galaxy... There doesn't appear to be any bright stars in that region so I'm at a bit of a loss.
I'm really not sure what to check next...

Any suggestions?
Thanks for looking!

Larry

[Gordon]

The first image is probably a satellite passing.

The second image looks like very high wispy clouds passing.

[Larry 1969]

The first image is probably a satellite passing.

The second image looks like very high wispy clouds passing.

Thanks Gordon, but that streak in the first image is in every one of my subs and, if you look closely, it is in the second image as well but it's orientation with the galaxy is the same. Almost like there is a super bright star just outside my image circle, but there isn't...

Larry

[STEVE333]

Hi Larry - Two thoughts:
1) Have you checked with Orion Service Dept.?
2) Have you checked to make sure the diagonal mirror is clean.

I'm just grasping at straws here. I know you probably already checked the diagonal mirror.

Steve

[Larry 1969]

Hi Larry - Two thoughts:
1) Have you checked with Orion Service Dept.?
2) Have you checked to make sure the diagonal mirror is clean.

I'm just grasping at straws here. I know you probably already checked the diagonal mirror.

Steve

Thanks Steve! Actually, I have not looked at the secondary mirror nor have I contacted Orion.
The second image is really poor but it was all I could do in 20 minutes of semi-clear sky. If you look closely you can see the streak.
I'll mark it so it stands out better.

Larry

[Larry 1969]

There.
I marked it in the original image.
Thanks for looking!

Larry

[dcrowson]

Is this NGC 891? If so, that streak appears to be in the direction of Almach. Before doing anything more drastic, point somewhere else and see if it goes away.

Dan

[Larry 1969]

Is this NGC 891? If so, that streak appears to be in the direction of Almach. Before doing anything more drastic, point somewhere else and see if it goes away.

Dan

Thanks Dan! It is indeed NGC 891. It is not in any of my other images. If it is Almach, how should I image this galaxy? There doesn't seem to be a way around it...

Larry

[Larry 1969]

I just opened Stellarium and checked out my FOV. Almach is pretty far outside my FOV so I wouldn't think it would influence the image, but the angle seems to point to it. Here's a Stellarium screenshot that shows my FOV and Almach. The camera rotation is wrong but, if you draw a line from the edge of the galaxy to Almach, it looks like my image...

Larry

[STEVE333]

Is it possible the Explore Scientific Coma Corrector is causing the problem? Is it being used for these pictures?

Trying to image without the Coma Corrector would answer the question. However, that may be a lot of work.

Steve

[Larry 1969]

Is it possible the Explore Scientific Coma Corrector is causing the problem? Is it being used for these pictures?

Trying to image without the Coma Corrector would answer the question. However, that may be a lot of work.

Steve

I am using the coma corrector in these images but I've never shot without it and this problem doesn't exist in any of my other images.
It really seems like there is something in this part of the sky causing the issue but what? Others have imaged this galaxy without issue.

Larry